DumpMempool: Pass in dump_path, stop using gArgs

Also introduce node::{ShouldPersistMempool,MempoolPath} helper functions
in node/mempool_persist_args.{h,cpp} which are used by non-kernel
DumpMempool callers to determine whether or not to automatically dump
the mempool and where to dump it to.

src/Makefile.am

@@ -198,6 +198,7 @@ BITCOIN_CORE_H = \
   node/chainstate.h \
   node/coin.h \
   node/context.h \
+  node/mempool_persist_args.h \
   node/miner.h \
   node/minisketchwrapper.h \
   node/psbt.h \
@@ -380,6 +381,7 @@ libbitcoin_node_a_SOURCES = \
   node/context.cpp \
   node/eviction.cpp \
   node/interfaces.cpp \
+  node/mempool_persist_args.cpp \
   node/miner.cpp \
   node/minisketchwrapper.cpp \
   node/psbt.cpp \

src/init.cpp

@@ -41,6 +41,7 @@
 #include <node/chainstate.h>
 #include <node/context.h>
 #include <node/interface_ui.h>
+#include <node/mempool_persist_args.h>
 #include <node/miner.h>
 #include <policy/feerate.h>
 #include <policy/fees.h>
@@ -111,6 +112,8 @@ using node::CleanupBlockRevFiles;
 using node::DEFAULT_PRINTPRIORITY;
 using node::DEFAULT_STOPAFTERBLOCKIMPORT;
 using node::LoadChainstate;
+using node::MempoolPath;
+using node::ShouldPersistMempool;
 using node::NodeContext;
 using node::ThreadImport;
 using node::VerifyLoadedChainstate;
@@ -246,8 +249,8 @@ void Shutdown(NodeContext& node)
     node.addrman.reset();
     node.netgroupman.reset();
 
-    if (node.mempool && node.mempool->IsLoaded() && node.args->GetBoolArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL)) {
+    if (node.mempool && node.mempool->IsLoaded() && ShouldPersistMempool(*node.args)) {
-        DumpMempool(*node.mempool);
+        DumpMempool(*node.mempool, MempoolPath(*node.args));
     }
 
     // Drop transactions we were still watching, and record fee estimations.

src/node/mempool_persist_args.cpp

@@ -0,0 +1,23 @@
+// Copyright (c) 2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <node/mempool_persist_args.h>
+
+#include <fs.h>
+#include <util/system.h>
+#include <validation.h>
+
+namespace node {
+
+bool ShouldPersistMempool(const ArgsManager& argsman)
+{
+    return argsman.GetBoolArg("-persistmempool", DEFAULT_PERSIST_MEMPOOL);
+}
+
+fs::path MempoolPath(const ArgsManager& argsman)
+{
+    return argsman.GetDataDirNet() / "mempool.dat";
+}
+
+} // namespace node

src/node/mempool_persist_args.h

@@ -0,0 +1,19 @@
+// Copyright (c) 2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_NODE_MEMPOOL_PERSIST_ARGS_H
+#define BITCOIN_NODE_MEMPOOL_PERSIST_ARGS_H
+
+#include <fs.h>
+
+class ArgsManager;
+
+namespace node {
+
+bool ShouldPersistMempool(const ArgsManager& argsman);
+fs::path MempoolPath(const ArgsManager& argsman);
+
+} // namespace node
+
+#endif // BITCOIN_NODE_MEMPOOL_PERSIST_ARGS_H

src/rpc/mempool.cpp

@@ -8,6 +8,7 @@
 #include <chainparams.h>
 #include <core_io.h>
 #include <fs.h>
+#include <node/mempool_persist_args.h>
 #include <policy/rbf.h>
 #include <policy/settings.h>
 #include <primitives/transaction.h>
@@ -19,6 +20,8 @@
 #include <util/moneystr.h>
 
 using node::DEFAULT_MAX_RAW_TX_FEE_RATE;
+using node::MempoolPath;
+using node::ShouldPersistMempool;
 using node::NodeContext;
 
 static RPCHelpMan sendrawtransaction()
@@ -721,12 +724,14 @@ static RPCHelpMan savemempool()
         throw JSONRPCError(RPC_MISC_ERROR, "The mempool was not loaded yet");
     }
 
-    if (!DumpMempool(mempool)) {
+    const fs::path& dump_path = MempoolPath(args);
+
+    if (!DumpMempool(mempool, dump_path)) {
         throw JSONRPCError(RPC_MISC_ERROR, "Unable to dump mempool to disk");
     }
 
     UniValue ret(UniValue::VOBJ);
-    ret.pushKV("filename", fs::path((args.GetDataDirNet() / "mempool.dat")).u8string());
+    ret.pushKV("filename", dump_path.u8string());
 
     return ret;
 },

src/test/fuzz/validation_load_mempool.cpp

@@ -4,6 +4,7 @@
 
 #include <chainparamsbase.h>
 #include <mempool_args.h>
+#include <node/mempool_persist_args.h>
 #include <test/fuzz/FuzzedDataProvider.h>
 #include <test/fuzz/fuzz.h>
 #include <test/fuzz/util.h>
@@ -15,6 +16,8 @@
 #include <cstdint>
 #include <vector>
 
+using node::MempoolPath;
+
 namespace {
 const TestingSetup* g_setup;
 } // namespace
@@ -37,5 +40,5 @@ FUZZ_TARGET_INIT(validation_load_mempool, initialize_validation_load_mempool)
         return fuzzed_file_provider.open();
     };
     (void)LoadMempool(pool, g_setup->m_node.chainman->ActiveChainstate(), fuzzed_fopen);
-    (void)DumpMempool(pool, fuzzed_fopen, true);
+    (void)DumpMempool(pool, MempoolPath(g_setup->m_args), fuzzed_fopen, true);
 }

src/validation.cpp

@@ -4726,7 +4726,7 @@ bool LoadMempool(CTxMemPool& pool, CChainState& active_chainstate, FopenFn mocka
     return true;
 }
 
-bool DumpMempool(const CTxMemPool& pool, FopenFn mockable_fopen_function, bool skip_file_commit)
+bool DumpMempool(const CTxMemPool& pool, const fs::path& dump_path, FopenFn mockable_fopen_function, bool skip_file_commit)
 {
     auto start = SteadyClock::now();
 
@@ -4749,7 +4749,7 @@ bool DumpMempool(const CTxMemPool& pool, FopenFn mockable_fopen_function, bool s
     auto mid = SteadyClock::now();
 
     try {
-        FILE* filestr{mockable_fopen_function(gArgs.GetDataDirNet() / "mempool.dat.new", "wb")};
+        FILE* filestr{mockable_fopen_function(dump_path + ".new", "wb")};
         if (!filestr) {
             return false;
         }
@@ -4775,7 +4775,7 @@ bool DumpMempool(const CTxMemPool& pool, FopenFn mockable_fopen_function, bool s
         if (!skip_file_commit && !FileCommit(file.Get()))
             throw std::runtime_error("FileCommit failed");
         file.fclose();
-        if (!RenameOver(gArgs.GetDataDirNet() / "mempool.dat.new", gArgs.GetDataDirNet() / "mempool.dat")) {
+        if (!RenameOver(dump_path + ".new", dump_path)) {
             throw std::runtime_error("Rename failed");
         }
         auto last = SteadyClock::now();

src/validation.h

@@ -1017,7 +1017,7 @@ bool DeploymentEnabled(const ChainstateManager& chainman, DEP dep)
 using FopenFn = std::function<FILE*(const fs::path&, const char*)>;
 
 /** Dump the mempool to disk. */
-bool DumpMempool(const CTxMemPool& pool, FopenFn mockable_fopen_function = fsbridge::fopen, bool skip_file_commit = false);
+bool DumpMempool(const CTxMemPool& pool, const fs::path& dump_path, FopenFn mockable_fopen_function = fsbridge::fopen, bool skip_file_commit = false);
 
 /** Load the mempool from disk. */
 bool LoadMempool(CTxMemPool& pool, CChainState& active_chainstate, FopenFn mockable_fopen_function = fsbridge::fopen);